Previously, there have been attempts to provide a flexible, economical and reliable control system to regulate the operational characteristics of vehicle turbochargers used in association with internal combustion engines. Presently, the most common control for turbocharger operation is an exhaust waste gate. The waste gate controls output pressure of the turbocharger by bypassing exhaust gas around the turbine portion or driving side of the turbocharger. The waste gate control technical is used on racing engines and subsequently has been adapted to use on other vehicles where increased performance is desired from a given engine. One disadvantage of the waste gate technic is its relative inflexibility in controlling boost and turbocharger operation in accord with engine requirements. Another disadvantage is the thermal inefficiency resulting from bypassing the exhaust energy of a portion of the exhaust.
A more efficient, flexible and therefore desirable process or technic for controlling the operation of a turbocharger is to selectively vary the size of the turbocharger's intake for the exhaust gases. Using this technic, the turbine side or driving portion of the turbocharger is continuously exposed to a regulated exhaust flow and thus the speed of the turbocharger may be easily maintained at a desired operational speed. Resultantly, the turbocharger is controlled to be always ready to generate sufficient boost pressure for the engine as dictated by the operator's throttle movement. A particularly desirable type of intake control for a turbocharger turbine utilizes a plurality of pivotally mounted vanes which are circularly arranged about and upstream of the turbocharger's turbine blades. These vanes control and direct the exhaust gas flow to the turbine portion and specifically the turbine blades. The vanes are interconnected and are mounted so that they pivot or move simultaneously between a more closed position and a fully open position. In a more closed position, overlapping portions of the vanes substantially inhibit exhaust gas flow to the turbine blades. In a fully opened position, the vanes are least inhibitive to exhaust gas flow. Prior U.S. Pat. Nos. which disclose variable turbochargers of this type are: 4,179,247 to Osborn; 4,378,960 to Lenz; 4,403,913 to Fisker.